Nitric acid is manufactured on large scale by the catalytic oxidation of ammonia in Ostwald’s method. In this method ammonia is allowed to react with the excess of air in the’ presence of platinum, the catalyst at 600°C to produce nitric oxide (NO) gas and steam in the catalytic chamber or converter. The catalyst is used in the form of gauze. About 96% of ammonia is converted into nitric oxide.
Since the reaction is exothermic, so once started the heat released during the reaction maintains, the catalytic action at the required temperature. The nitric oxide formed is cooled by passing through coolers up to 150°C.
Nitric oxide is then mixed with an excess of air in the oxidation chamber to produce nitrogen dioxide i.e. nitrogen, peroxide (N02)
Nitrogen peroxide (N02) produced is directly dissolved in water: to I produce nitric acid, liberating nitric oxide gas in the absorption chamber. I Nitric oxide gas thus obtained is recycled to get more nitric acid.
Nitric acid obtained from this process is 68% concentrated which I can be concentrated further by passing over cone H2S04 up to 98 %.